North Atlantic climate far more predictable than models imply.

Quantifying signals and uncertainties in climate models is essential for the detection, attribution, prediction and projection of climate change1-3. Although inter-model agreement is high for large-scale temperature signals, dynamical changes in atmospheric circulation are very uncertain4. This leads to low confidence in regional projections, especially for precipitation, over the coming decades5,6. The chaotic nature of the climate system7-9 may also mean that signal uncertainties are largely irreducible. However, climate projections are difficult to verify until further observations become available. Here we assess retrospective climate model predictions of the past six decades and show that decadal variations in North Atlantic winter climate are highly predictable, despite a lack of agreement between individual model simulations and the poor predictive ability of raw model outputs. Crucially, current models underestimate the predictable signal (the predictable fraction of the total variability) of the North Atlantic Oscillation (the leading mode of variability in North Atlantic atmospheric circulation) by an order of magnitude. Consequently, compared to perfect models, 100 times as many ensemble members are needed in current models to extract this signal, and its effects on the climate are underestimated relative to other factors. To address these limitations, we implement a two-stage post-processing technique. We first adjust the variance of the ensemble-mean North Atlantic Oscillation forecast to match the observed variance of the predictable signal. We then select and use only the ensemble members with a North Atlantic Oscillation sufficiently close to the variance-adjusted ensemble-mean forecast North Atlantic Oscillation. This approach greatly improves decadal predictions of winter climate for Europe and eastern North America. Predictions of Atlantic multidecadal variability are also improved, suggesting that the North Atlantic Oscillation is not driven solely by Atlantic multidecadal variability. Our results highlight the need to understand why the signal-to-noise ratio is too small in current climate models10, and the extent to which correcting this model error would reduce uncertainties in regional climate change projections on timescales beyond a decade.

Preclinical evaluation of amiodarone for the treatment of murine leukemia P388. In vivo and in vitro investigation.

PURPOSE: The purpose of the present study was the investigation of antileukemic effect of amiodarone in leukemia P388 BDF1 bearing mice and its genotoxic and cytostatic effect in cultured normal human lymphocytes. METHODS: Leukemia P388 was used in this study. BDF1 mice were used for chemotherapy evaluation in vivo. The antitumor activity was assessed by the oncostatic parameter T/C, representing the increase of life span of drug-treated animals vs. controls. Lymphocyte cultures were used to study the genotoxic and cytostatic effect in vitro, expressed by enhanced sister chromatid exchange (SCE) and reduced proliferation rate indices (PRIS). RESULTS: Amiodarone was found to exert antileukemic potency against leukemia P388 bearing mice at all three different treatment schedules used, yielding T/C values of 155%, 163% with one cure and 230%. In the in vitro cytogenic experiments, significant increase of SCE rates by amiodarone was observed at 0.2 µM, while at the same concentration significant suppression of PRIS was achieved. CONCLUSION: According to the National Cancer Institute (NCI), a compound is characterized as potential chemotherapeutic deserving further evaluation if it produces T/C values≥125%. On the other hand the SCE assay has predictive value as a clinical assay for drugs exhibiting a strong correlation between cell killing and induction of SCEs. Further studies are warranted to clarify the structure-activity relationship of amiodarone.

Mandibular sarcoma as a second neoplasm following radiotherapy for a nasopharyngeal carcinoma in childhood (case report).

We report an unusual case of mandibular sarcoma which developed in the field of irradiation of a patient treated successfully 10 years previously for nasopharyngeal carcinoma (NC). Although second malignant neoplasms are not rare among survivors of childhood cancer, this event is not included among the type of failures and complications of treatment of NC occurring either in children.

Predictive values of CA 125 antigen levels and CT scan in second-look procedures for ovarian cancer.

23 patients with ovarian cancer were investigated 10 days after their last regimen of chemotherapy by CT scan and CA 125 in comparison with 'second-look' findings. In 17 out of 23 cases the CT scan results correlated with the operative ones. There were 6 false-negative findings but no false-positives. In all cases serum CA 125 levels correlated with the second-look operation. Our data suggest that the upper limit of CA 125, especially for patients, with negative findings, is less than or equal to 20 U/ml which is much lower than that of 35 U/ml, which is generally accepted. They also indicate the value of CA 125 in the detection of persistent ovarian cancer and the value of the CT scan in the detection of liver metastases. According to the above findings we question the value of the second-look operation in certain cases of ovarian cancer.

Comparative study of RIS with the 131I-OC 125 F(ab')2 Mab and CT scan prior to second look operation for ovarian cancer.

A tumour-associated radiolabelled monoclonal antibody (Mab) 131I-OC 125 F(ab')2 was used to investigate 27 patients 2 weeks after their last chemotherapy regimen and prior to second-look surgery for ovarian cancer. We did compare the radioimmunoscintigraphy (RIS) findings with the CT scan results and the second-look operation data. In 23 out of 27 cases the RIS results correlated with the operation findings, while there were four false-negative results. Computed tomography (CT) scans correlated in 17 out of 23 cases with the operative findings, while there were six false-negative results. We concluded that RIS is more specific in detecting the tumour site within the pelvis, while CT scan is superior in detecting liver metastases.